1. The Field of the Invention
This invention relates to improvements in wave motor tanks and more particularly to that class of wave motor tank which is useful at extracting energy from tidal and wave motion of large bodies of water due to the rise and fall thereof.
2. Description of the Prior Art
The prior art abounds with wave motor apparatuses, a major class of which utilizing reciprocally operating tanks which are buoyantly supported by a body of water. Such tanks frequently require vertical guidance and utilize cables, chains or rigid members, which when coupled to the tank, transmit a force therealong due to the displacement of such tank when the tank shifts its position in response to wave motion and the tides. Typical of such a wave motor, is the apparatus taught in U.S. Pat. No. 884,080 issued Apr. 7, 1908, to G. T. Fallis. Fallis discloses a buoyant sealed tank having a pair of racks upstanding therefrom, which is vertically guided and allowed to rest in and on a body of water. A platform is provided, having supporting columns anchored in the soil beneath the body of water. The columns pass through openings in the platform and each engage a pair of pinion gears, carried on a common shaft, each pinion is mounted on a separate one-way clutch such that the shaft is caused to rotate in one direction at all times, responsive to the buoyant forces directing the tank in an upward direction as the tide comes in, for example, and responsive to the weight of the tank when the tide goes out. Similarly, swells and wave motion further cause the output shaft to rotate in the same direction due to the waves' effect upon the tank. The output shaft is provided with a pulley for purposes of coupling such shaft to an electric generator or the like. Unfortunately, the forces transmitted to the output shaft, when the tank is moving in an upward direction, are limited to a force equivalent to the net buoyancy of the tank. When the tank descends, as when the tide or waves permit same, the only force transmitted to the pair of racks thereof is a downward force of the same magnitude as the upward force. This is so because the weight of the tank must always be slightly less than the buoyant forces exerted thereon. Since it is presumed that the tank is always in contact with the water, the buoyant forces are always at work. Thus, the torque transmitted to the output shaft, regardless of direction taken by the Fallis tank is proportional to the difference between the buoyant forces exerted on the tank less the weight thereof. Friction, induced by the vertical posts providing vertical guidance for the tank, further diminishes the efficiency of the system. Such vertical posts are required because the Fallis tank is susceptible to horizontal motion of the water about the tank which tends not only to displace the tank laterally but tends, more importantly, to shift the line of motion of the tank away from the vertical.
U.S. Pat. No. 3,894,241 issued July 8, 1975 to S. Kaplan discloses a power source which is powered by the energy in water waves that has a frame which supports a shaft above the waves. A large number of floats are constrained by the frame to be moved up and down under the shaft by the waves. Above each float a first pulley having a first releasable ratchet and a non-releasable ratchet has a chain pass over it to hold a first weight at one end. On each float there is mounted a second pulley which engages the other end of the chain, the second pulley having a second releasable ratchet. Each chain passes through a passage in the float to terminate a second lighter weight. As waves move each float up, a second releasable ratchet allows its second pulley to turn. As each float moves down, it pulls a chain about a first pulley raising a first weight, a first releasable ratchet allowing its first pulley to turn and a non-releasable ratchet allowing it to turn without rotating the shaft. As each first weight reaches a desired height, a means releases both releasable ratchets to drop each first weight to turn the shaft by means of the first pulley and the non-releasable ratchet. Sufficient floats and associated weights and apparatus insure that the shaft will be constantly turning by falling weights to provide a power source. Each of the floats are maintained in a vertical guidance system and each provides a turning force to the shaft utilizing the chains therefor. The Kaplan apparatus requires that the total weight of the float must be greater than the difference between the individual weights associated therewith. In this manner, when a large number of floats are employed, at least one of the weights will always be falling so as to provide a constant power output to the shaft. The Kaplan apparatus teaches a mechanism which is effective in providing a turning force to the output shaft which is best suited for use with a float which cannot descend as rapidly as the water in the region adjacent thereto. Obviously, when the floats utilized by Kaplan are made sufficiently large, such floats will respond to wave and tide actions and reside in the water at all times. This effectively removes the advantage of the Kaplan apparatus such that the net force applied to the Kaplan chain when the float operating such chain moves in the downward direction is equivalent to the difference between the weight of the float and the buoyant forces of the water always contacting same.